/**
* Counts the rows from the {@code scanner} until exhaustion. It doesn't require the scanner to be
* new, so it can be used to finish scanning a previously-started scan.
*/
protected static int countRowsInScan(AsyncKuduScanner scanner) throws Exception {
final AtomicInteger counter = new AtomicInteger();
Callback<Object, RowResultIterator> cb =
new Callback<Object, RowResultIterator>() {
@Override
public Object call(RowResultIterator arg) throws Exception {
if (arg == null) return null;
counter.addAndGet(arg.getNumRows());
return null;
}
};
while (scanner.hasMoreRows()) {
Deferred<RowResultIterator> data = scanner.nextRows();
data.addCallbacks(cb, defaultErrorCB);
data.join(DEFAULT_SLEEP);
}
Deferred<RowResultIterator> closer = scanner.close();
closer.addCallbacks(cb, defaultErrorCB);
closer.join(DEFAULT_SLEEP);
return counter.get();
}
/**
* Register a callback and an "errback".
*
* <p>This has the exact same effect as {@link Deferred#addCallbacks(Callback, Callback)} keeps
* the type information "correct" when the callback and errback return a {@code Deferred}.
*
* @param d The {@code Deferred} we want to add the callback and errback to.
* @param cb The callback to register.
* @param eb The errback to register.
* @return {@code d} with an "updated" type.
*/
@SuppressWarnings("unchecked")
public static <T, R, D extends Deferred<R>, E> Deferred<R> addCallbacksDeferring(
final Deferred<T> d, final Callback<D, T> cb, final Callback<D, E> eb) {
return d.addCallbacks((Callback<R, T>) ((Object) cb), (Callback<R, E>) ((Object) eb));
}